1. Field of the Invention
The present invention relates to a position sensing device, and more particularly, to an optical fiber position sensor for determining the position, or location, at any given time of an element rotationally movable with respect to another element fixed relative to the movable element.
2. Description of the Prior Art
In present day flight control systems, the position of most actuator control surfaces of an aircraft are sensed with an electromagnetic, linearly variable, differential transformer (LVDT). The conventional electromagnetic LVDT is an extremely simple device with high linearity and nearly infinite resolution, and which can operate in rather adverse environments (high and low temperatures, vibration, shock, etc.). However, conventional LVDT's are bulky and heavy, require special frequency excitation, and produce amplitude modulated AC output signals which are cumbersome to convert. Furthermore, a quad-redundant actuator requires a total of 16 LVDT's, a significant volume and weight. Since reduction of component weight and size is given high priority in aircraft design, it is desirable to provide an actuator position sensor which is smaller, lighter in weight, and simpler of construction and operation than the conventional LVDT.
In anticipation of increased use of optical components in flight control systems, starting with a fiber optic data link and eventually leading to a totally fly-by-light system, actuator position sensors must interface with other optical components. The above features, therefore, can only be effectively achieved with a direct optical to optical interface.
It is therefore an object of the present invention to provide a position sensor which is simpler, smaller, and lighter in weight than conventional LVDT's and which is, at the same time, capable of performance equal to or better than that available with conventional LVDT's and which requires a minimum of interface hardware and is compatible with a fly-by-light system.